In the Ventura et al. U.S. Pat. No. 4,884,388 for LETTUCE PACKER, an apparatus was set forth for producing by automated lettuce packing, a carton of packed lettuce that was superior to a similar carton packed by hand. This apparatus, so far as is relevant herein, can be summarized by first describing the lettuce holding trays, secondly setting forth the configuration of the packing station (hereinafter referred to as the "plunging station"), and thereafter describing briefly the superiority of the resulting packed carton over the hand packed carton of the prior art.
The Ventura et al. Patent disclosed a lettuce holding tray. The purpose of the tray was to hold packed lettuce, transport the packed lettuce, and allow the lettuce to be moved as packed from the tray to an awaiting carton for shipment in the carton to market.
The type of packing here utilized is the so-called "naked pack" of lettuce within a carton. In the naked pack technique, lettuce heads are placed side-by-side within a carton without the lettuce being either wrapped or held by separating material.
The trays are fabricated to hold a single layer of lettuce being placed within a box. Lettuce is typically packed two layers high within a receiving box. Each of these layers includes the placement of four rows of lettuce in packed side-by-side relation with each row being three heads wide.
The tray includes longitudinal and transverse upper members defining a matrix of interstitial lettuce receiving cells therebetween. The defined matrix circumscribes individual cells surrounding each head of lettuce in a layer of a box. Thus the matrix of the tray defines a series of lettuce receiving cells having four rows, each row with three side-by-side positions for receiving a total of twelve heads of lettuce.
Cell sides are provided for allowing the lettuce placed in each cell to be held in each cell and further for permitting lettuce to be packed from each cell by being plunged out of the cell through the bottom of the tray. Specifically, the cell sides comprise sheets of flexible material fastened at the top to the matrix. The sheets of flexible material depended from the matrix inwardly of each cell. These flexible tray sides are preferably fabricated from stainless steel sheet metal.
The function of the flexible sides of the cells of the tray is easily understood. Lettuce placed within the cell is oriented to the desired packed disposition in the carton and thereafter held to the cell by the flexible sides in its desired orientation. A fully packed tray having the lettuce held in each cell therein can be transported from a station where it is packed to another station where it is plunged to a carton.
The removal of the lettuce from the tray is likewise easy to understand. Specifically, an array of plungers is utilized. Similar to the rows of cells in the lettuce receiving tray, the plunger array includes four rows of three side-by-side plungers. These plungers are oriented to and toward a tray positioned between the overlying plungers and the underlying carton.
The plungers simultaneously move through a tray packed with heads of lettuce oriented to their desired packed orientation. The lettuce moves out of the tray and into the carton without changing the original orientation that the lettuce had in the holding and transporting tray. Packing of a single layer of the carton occurs with a single simultaneous stroke of the twelve plungers of the plunger array.
In the Ventura et al. Patent, a single array of twelve plungers was utilized. Consequently, packing of the lower layer of a lettuce carton first occurs. Thereafter--and utilizing the same plunging mechanism--packing of the upper layer occurs. There results a packed carton of lettuce having demonstrably improved characteristics.
The superiority of the machine packed lettuce can be summarized. The heads of lettuce as packed by the plungers move without relative rotation one to another as they pass from the tray to the carton. An entire layer of the lettuce carton is packed by the plunger array at a single stroke; this is an operation that is not possible to duplicate by hand. There results a regularity in the packing of each of the two layers of the carton that is readily discernable upon the opening of the carton. The outer lettuce leaves of the carton form an almost square perimeter. These leaves of lettuce, while having this square perimeter, have minimal spoilage. This regularity of lettuce head packing enables the product to be shipped with greatly reduced damage. As a consequence, cartons of lettuce packed in accordance with this "naked" pack technique ship with less deterioration to the conventional hand packed "naked" lettuce and command a premium price over conventional hand packed lettuce equivalents.
The Ventura et al. Patent was primarily directed to the packing process described. Although it was suggested that the trays be disposed to the workers at elevations and angles where the lettuce holding trays could most conveniently be packed, a commercially practical packing station was not disclosed. Moreover, provision for the smooth flow of lettuce through the packing station including loading from a conveyor having empty trays, packing at the station, and conveyance to d conveyor having full trays was set forth in a prototype configuration only.